Depending on the terms of leaving history may repeat itself. If there is a hard exit and a major economic downturn then I suspect the UK will hurriedly sign up to the EEA like it did with the EEC back in the early 70s. Of course, make then it still took an IMF bailout and at least another decade to get back on its feet. Hopefully it wouldn't be sever it if happened again, seeing as the UK is now economically stronger than it was post war.